Editors File Associations window is very wide

In the File Associations window a number of entries have



 many "locked by" descriptions. This has the effect of making the window very wide and hiding the Add/Default
buttons way to the right where a newbie like me has trouble finding them.

So
1. Does anyone know of a way forcing the screen layout smaller or
2. Suppressing/removing the "locked by" descriptions.

Be gentle....very new at this.
Hank
(3270 green screen is my friend - much less real estate !)